Locking arrangement for side-entry blades

ABSTRACT

An arrangement is provided for installing and subsequent locking of side-entry blades in a turbine rotor disc. Heretofore, the placement of the last blade in a circular row of turbine blades has required twisting, bending and distorting of the last and adjacent blade at assembly because of interference between adjacent blades. This jeopardized their reliability in service. The present arrangement permits radial entry of the last blade into the rotor or disc without distortion of any of the blades.

United States Patent [72] Inventors DonlldlLRupp References Cited Media;

060x 2 20 mm? 111B 444% 4 S m.mm M m m m T t A m m m P" "E m m mm EL m"Ta n m A f "3N T e e v..b G wm m e0 wHGPLm 6090 N2556 ww I/HH 502 3575.nwwm 5 8 2 ?0 8272 -222 m P C 0 m m w u 0 m C n k m u s. m m 9... h 67m99 ll A B 9 n nummw o N mm mam a AFPA HUSH UHHU Pittsburgh, Pl.

369,127 3/1932 Great Britain................ 416/219 Primary Examiner-Everette A. Powell. .I r. H Attorneys-A. T. Stratton, F. P. Lyle and F.Cristiano. Jr.

ABSTRACT: An arrangement is provided for installing and [54] ARRANGEMENTFOR SIDE'ENTRY subsequent locking of side-entry blades in a turbinerotor disc. 4 Claims 4 Dnwin Fi Heretofore, the placement of the lastblade in a circular row of 8 turbine blades has required twisting,bending and distorting of [52] US. the last and adjacent blade atassembly because of interference between adjacent blades. Thisjeopardized their reliability in service. The present arrangementpermits radial entry of the last blade into the rotor or disc withoutdistortion of any of the blades.

62 2 m93 4 2 w n m m xn 4 M N6 M2 m5 .1 m2

[51] [50] Field of Search.

PAT ENTED on: I 4 ism LOCKING ARRANGEMENT FOR SIDE-ENTRY BLADESBACKGROUND OF THE INVENTION This invention relates, generally, toturbine rotors and, more particularly, to an arrangement for installingand securing turbine rotor side-entry blades in the periphery of a bladesupporting disc.

During the construction of prior turbines, the placement of the lastblade in a circular row of turbine rotor side-entry blades requiredtwisting, bending and distortion of the last and adjacent blade atassembly because of interference between the blades. This distortion ofthe blades jeopardized their reliability duringoperation of the turbine.

SUMMARY OF THE INVENTION In accordance with one embodiment of theinvention, the lateral width of the platform portion of a turbine rotorsideentry blade which is to be installed last in the periphery of arotor disc is reduced sufficiently to permit the blade to be insertedradially between the two adjacent blades without distortion of any ofthe blades. After the blade has been inserted to the bottom of thereceiving channel, it is moved laterally to its operating positionadjacent to the first blade installed and secured by means of a lockingmember which is inserted axially in a subchannel in the rotor disc. Thelocking member has a radially extending projection thereon which closedthe space between the platforms of the last blade and the next to thelast blade installed in a circular row of sideentry blades.

BRIEF DESCRIPTION OF THE DRAWING For a better understanding of thenature of the invention, reference may be had to the following detaileddescription, taken in conjunction with the accompanying drawing, inwhich:

FIG. I is a diagrammatic view, partly in vertical section and partly inelevation, of a portion of a turbine rotor assembly embodying principalfeatures of the invention;

FIG. 2 is an enlarged view, similar to FIG. 1, showing the last blade ofa circular row of blades in its partly assembled position; and

FIGS. 3 and 4 are diagrammatic views, in plan, showing the manner ofinstalling the last blade in a circular row of blades.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing,particularly to FIG. I, there is shown a portion of a rotor 11 for anaxial flow turbine of a type well known in the art. The rotor 11comprises a disc 12 having a peripheral portion I3 with a plurality ofaxially extending serrated channels I4 circumferentially spaced aroundits periphery for receiving serrated root portions 15 of turbine rotorblades 16 of the side-entry type. In addition to the root portion I5,each blade 16 includes an airfoil portion 17 (partly shown) and aplatform portion 18 joining the root portion to the airfoil portion. Theserrations 19 on the channel 14 intermesh with the serrations 20 on theroot portion 15 to withstand the centrifugal force developed by therotation of the rotor and secure thev blade in the channel. After theblades are installed in the channels, keys (not shown) of a type wellknown in the art are utilized to prevent axial movement of the blades.

As shown in FIGS 3 and 4, the blades 16 may be provided with a lashingstructure 6 of the type described in U.S. Pat. No. 2,472,886 issued June14, 1949 to J. D. Conrad and W. H. Lloyd and assigned to WestinghouseElectric Corporation. The lashing structure includes projections 7formed integrally with the airfoil portions 17 of the blades andextending outwardly with their outer ends disposed contiguously andconnected, as by a welded joint located approximately midway betweenblades. The lashing structure reduces vibration of the blades.

0f the three blades 16 shown in FIG. 1, it may be assumed that blade 21is the first one installed, blade 22 is next to the last one and blade23 is the last one installed in a circular row of side-entry blades.I-Ieretofore, the installation of the last blade has required twisting,bending and distorting of the last and adjacent blade in order to insertthe last blade into its channel from the side of the disc because ofinterference between adjacent blades as shown in FIG. 3. The distortionof the blades jeopardized their reliability in service.

In order to permit installation of the last blade without distortion ofany of the blades, the lateral width of the platform portion 18a of theblade 23 is reduced sufficiently to permit the blade 23 to be insertedradially from above into its channel between adjacent blades 21 and 22as shown by dot-dash lines in FIGS. 2 and 4. In this manner, the lastblade 23 can be installed without distortion of any of the blades.

After the blade 23 is inserted radially to the bottom of the channel140, it is moved laterally to the right as viewed in FIG. 2 to theposition shown in FIG. I and is secured in position by means of alocking member 25 which is inserted axially into a subchannel 24. Thesubchannel 24 has serrations 26 thereon which mesh with serrations 27 onthe locking member 25 to secure it in the subchannel 24. Likewise, thelocking member 25 has serrations 29 thereon which mesh with theserrations 20 on the root portions of the blades 23 and 22 to maintainthe blades in laterally spaced relation and secure the blades in theiroperating positions.

As shown in FIG. I, the locking member 25 has a radially extendingprojection 30 thereon which closes the space between the platformportions 18 and 18a of adjacent blades 22 and 23, respectively. In thismanner, leakage of the motive fluid between the platform portions isprevented. The locking piece 25 may be keyed in a manner similar to theblades 16 to prevent axial movement of the locking member duringoperation of the turbine.

From the foregoing description, it is apparent that the inventionprovides a locking arrangement which permits the installing andsubsequent locking of side-entry blades in a turbine rotor disc withoutdistortion of any of the blades, thereby improving the reliability ofthe blades in service. The arrangement can be economically manufacturedand utilized.

It will be noted by referring to FIG. I, especially, that the rootportions of the next to last blade 22 and the last blade 23 aresubstantially identical to each other and to the root portion of theother blades as exemplified by blade 21. Also, the locking member 25coacts with the rotor disc I2 to form two channels of identicalconfiguration to the channel I4, thereby simplifying manufacturing ofthe blades and roots.

We claim as our invention:

1. In a locking arrangement for a circular row of turbine rotorside-entry blades,

said rotor having a disc with a plurality of axially extending channelscircumferentially spaced around its periphery,

each blade having a root portion and an airfoil portion and a platformportion joining the root portion to the airfoil portion,

means on the root portion of each blade cooperating with means on achannel for securing the blade in the channel,

the lateral width of the platform portion of one of the blades beingless than the lateral width of the platform portions of the other bladesto permit said one blade to be inserted radially between two adjacentblades,

a locking member extending axially between said one blade and anadjacent blade to secure said one blade in its operation position, and

a radially extending projection on the locking member for closing thespace between the platform portions of said one blade and an adjacentblade.

2. The locking arrangement defined in claim 1, wherein:

said rotor disc has an axially extending subchannel for receiving saidlocking member.

3. The locking arrangement defined in claim 2, including:

means on the locking member cooperating with means on the subchannel forsecuring the locking member in the subchannel. 4. The lockingarrangement defined in claim 3, wherein: the locking member securingmeans includes intermeshing 5 serrations on the locking member and thesubchannei.

II I l i

1. In a locking arrangement for a circular row of turbine rotorside-entry blades, said rotor having a disc with a plurality of axiallyextending channels circumferentially spaced around its periphery, eachblade having a root portion and an airfoil portion and a platformportion joining the root portion to the airfoil portion, means on theroot portion of each blade cooperating with means on a channel forsecuring the blade in the channel, the lateral width of the platformportion of one of the blades being less than the lateral width of theplatform portions of the other blades to permit said one blade to beinserted radially between two adjacent blades, a locking memberextending axially between said one blade and an adjacent blade to securesaid one blade in its operation position, and a radially extendingprojection on the locking member for closing the space between theplatform portions of said one blade and an adjacent blade.
 2. Thelocking arrangement defined in claim 1, wherein: said rotor disc has anaxially extending subchannel for receiving said locking member.
 3. Thelocking arrangement defined in claim 2, including: means on the lockingmember cooperating with means on the subchannel for securing the lockingmember in the subchannel.
 4. The locking arrangement defined in claim 3,wherein: the locking member securing means includes intermeshingserrations on the locking member and the subchannel.